1. Field of the Invention
The present invention relates to a method and an apparatus for cutting an optical fiber.
2. Description of the Related Art
In order to properly join a pair of optical fibers, it is necessary that the surface of the connecting end of each fiber be flat and perpendicular to the fiber's axis. To provide such an end face, the distal end of each optical fiber needs to be properly cut prior to splicing the fibers. Conventionally, this fiber cutting has been done using a fiber cutting apparatus as shown in FIGS. 1A to 1C.
FIG. 1A illustrates an example of a conventional optical fiber cutting apparatus applicable to single-core fibers.
Reference numeral 10 denotes a first clamp, which comprises a clamp table 12 and a pincher 14.
Pincher 14 is freely openable and closable to clamp table 12, and, when closed, it calamps a sheathed portion 42 of an optical fiber 40.
Reference numeral 16 denotes a rubber member used to absorb the stress applied on sheathed portion 42 by pincher 14.
In FIGS. 1A-1C, pincher 14 is illustrated to move vertically with respect to clamp table 12. Actually, however, pincher 14 is often attached to clamp table 12 by means of a hinge 18 so as to be rockable to the clamp table, as shown in FIG. 2. The former design of first clamp 10 (see FIGS. 1A-1C) is the same as the latter design (FIG. 2) in principle and is easier to see its operation. In this respect, therefore, a second clamp 20 is also illustrated in the same manner so that its pincher 24 is shown to move vertically with respect to a clamp table 22.
Second clamp 20 comprises clamp table 22 and pincher 24. Pincher 24 is freely openable and closable to clamp table 22, and, when closed, it clamps an unsheathed or bare portion 44 (i.e., glass portion) of an optical fiber 40.
Reference numeral 26 denotes a rubber member used to absorb the stress applied on glass portion 44 by pincher 24.
Reference numeral 50 is a base for supporting clamp tables 12 and 22. Reference numeral 52 is a scoring blade provided between first clamp 10 and second clamp 20, which moves within a plane perpendicular to the axis of optical fiber 40 in the horizontal or arched direction and scores the optical fiber at the desired portion.
Reference numeral 54 is a pushing member which applies bending stress on the scored optical fiber 40 from the opposite side of the score to cut the fiber.
To clamp optical fiber 40, first, optical fiber 40 is placed on clamp tables 12 and 22, as shown in FIG. 1A, then first clamp 10 is closed (FIG. 1B), and finally, second clamp 20 is closed (FIG. 1C). Thereafter, scoring blade 52 is moved within a plane perpendicular to the axis of optical fiber 40 in the horizontal direction or the arched direction, to score the optical fiber at the desired portion. Then, pushing member 54 applies bending stress on the scored optical fiber 40 from the opposite side of the score to cut the fiber.
As the pinchers of the individual clamps are sequentially closed, thus increasing the number of the clamping procedures, (1) the overall clamping operation is troublesome. And this operation would become more troublesome as the number of the clamps in use increases. (2) If wrong procedures are taken to close the clamps, it may twist or deform optical fiber 40.
The conventional cutting apparatus further has the following shortcoming. FIG. 3 illustrates the cutting apparatus, applied to a single core fiber, in a different aspect. In FIG. 3, the same reference numerals as are used in FIGS. 1A-1C are also used to specify the corresponding sections, thus omitting their otherwise redundant explanation.
Reference numeral 62 is a third clamp.
Scoring blade 52 is provided between second clamp 20 and third clamp 62 and is movable in the horizontal direction or in the arched direction, to score bare fiber 44 at the desired portion.
To prepare an end face perpendicular to the axis of optical fiber 40, the score on the optical fiber should also be perpendicular to the fiber axis 88.
To achieve this, optical fiber 40 needs to be clamped perpendicular to the moving direction 90 of scoring blade 52. However, sheathed portion 42 of optical fiber 40 is normally rolled and naturally curvy, so that the optical fiber even clamped may not be held straight as shown in FIG. 3. Therefore, the moving direction of scoring blade 52 is not perpendicular to the axis 88 of optical fiber 40 and the score would not be perpendicular to the fiber axis accordingly.
The conventional cutting apparatus further has the following shortcoming. FIG. 4 illustrates the cutting apparatus, applied to a single core fiber, in another aspect. In FIGS. 4, 5A and 5B, the same reference numerals as are used in the previously-described diagrams are also used to specify the corresponding sections, thus omitting their otherwise redundant explanation.
Third clamp 62 comprises a clamp table 64 and pincher 66. Pincher 66 is freely openable and closable to clamp table 64, when closed, it clamps bare portion (i.e., glass portion) 44 of an optical fiber 40. Reference numeral 36 is a rubber member used to absorb the stress applied on glass portion 44 by pincher 66.
Scoring blade 52 is moved in the horizontal direction or in the arched direction, to score bare fiber 44 at the desired portion, and then pushing member 54 is pressed against bare fiber 44, the fiber is cut (FIG. 5A). Pushing member 54 is then retracted (FIG. 5B), releasing the stress on the cut portions of bare fiber 44, so that the cut end of the fiber 44 and the end of a waste bare fiber 44A are likely to hit against each other. This may chip off or make a crack on the end face of bare fiber 44.
The conventional cutting apparatus further has the following shortcoming. FIGS. 6 and 7 illustrate the cutting apparatus, applied to a single core fiber, in a still different aspect. In FIGS. 6 and 7, the same reference numerals as are used in the previously-described diagrams are also used to specify the corresponding sections, thus omitting their otherwise redundant explanation.
Reference numeral 92 is a base of the overall cutting apparatus, and numeral 94 is a set table.
In the case where the diameter of the sheathed portion of the optical fiber is relatively large, and the optical fiber has a single core and needs a constant cutting length L, as shown in FIGS. 6 and 7, sheathed portion 42 is stopped at the boundary between groove 82 and slit 84 of guide 80 so that the cutting length L becomes constant.
On the other hand, if the diameter of the sheathed portion is relatively small (about 0.25 mm.phi.) and the cutting length L varies (see FIG. 8), sheathed portion 42 does not have a tendency to be curvy so that groove 82 is sufficient and it is unnecessary to form slit 84 in second guide 80. Sheathed portion 42 can freely be move within grooves 76 and 82.
Reference numeral 96 is a scale on which the end face of the fiber to be cut is aligned so as to determine the cutting length L.
When this cutting apparatus is applied to cutting a multicore fiber, a stationary jig is mounted to optical fiber 40.
As should be apparent from the above explanation given with reference to FIGS. 6-9, different types of cutting apparatuses should be conventionally provided depending on the types and uses of optical fibers to be cut and variation in the cutting length.